| Xisha sea area is located in the continental slope area of the northwest South China Sea. Controlled by
continental margin tension and strike slip, it has experienced two tectonic evolution stages: faulted period and depression
period. Influenced by Yuedong, Red River, Hainan Island, and Xisha provenances, it fills the continental-transitionalmarine strata. There are many kinds of geological bodies such as volcano, gas chimney, MTC, channel, which give birth to
various types of seafloor topography. Based on abundant 2D and 3D seismic data, 3D visualization and other technologies
are applied to display the seafloor topography of Xisha sea area completely and intuitively. The seafloor is divided into 3
kinds of 3rd-order topography: submarine plain, submarine slope, and trough, which are subdivided into 9 kinds of 4thorder topography, including abyssal plain, abyssal channel, abyssal honeycomb, abyssal mountain, abyssal crescent,
abyssal cone, abyssal tadpole, abyssal trough, and abyssal zone. Combined with the geological conditions, the main
controlling factors of the formation and distribution of various topographies are analyzed: abyssal plain, abyssal channel,
and abyssal trough are mainly controlled by the tectonic framework in the faulted period and the late sedimentary filling;
abyssal honeycomb is associated with the MTC system; abyssal mountain is caused by volcanic activity, and the bottom
current has transformed it; the abyssal crescent is the product of the erosion of bottom current; abyssal cone, abyssal
tadpole, and abyssal zone are different shapes of submarine pockmarks caused by gas escape. This is helpful to the further
study of the structural characteristics, deep-water sedimentary types and distribution, geological body distribution and
ocean current in Xisha sea area. |
